Pressure gauges of the type having the combination of a Bourdon tube and a spring suspended movement commonly provide for span adjustment that establishes accurate beginning and end points over the pressure range of the indicia scale. Otherwise, such gauges are generally deficient in not providing for linearity adjustment along the intermediate points between the ends.
National standard ASME B-40.1 establishes the standard of accuracy by which the suspended movement type gauges can qualify for "grade A" or closer accuracy. In accordance therewith, pointer rotation is required to be closely tailored to conform with the placement of increments shown on the dial face. Prior attempts toward linearizing have required special, costly, and impractical design changes of the segment gear. Further, any adjustment could only be effected with some degree of disassembly as with the case removed, rendering it necessary to conduct a final inspection for accuracy after complete re-assembly of all gauge components. Such added operations have heretofore made linearity adjustment impractical from a product cost standpoint.